A rare algal bloom has shut down shellfishing in Lake Tashmoo during a week where other Vineyard swimming spots were closed because of bacteria.

Seth’s Pond, the popular swimming hole in West Tisbury, has been closed to swimmers for more than a week because of high levels of enterococcus bacteria. The same bacteria led to a brief closure of Pay Beach in Oak Bluffs.

Starting Wednesday, Lake Tashmoo was closed to shellfishing because of a toxic algae bloom that some said is rare to Vineyard ponds.

Lake Tashmoo, which had been closed to shellfishing because of a rare toxic algae bloom, reopened Friday morning.

A press release from the town of Tisbury said that the state notified shellfish constable Danielle Ewart on Friday morning to say that additional testing indicated the pond had been cleared and that it could be reopened to shellfishers immediately.

Ms. Ewart discovered the bright pink algae bloom called prorocentrum lima in the outside flats of Lake Tashmoo a few weeks ago. The algae has been associated with diarrheal shellfish poisoning.